Merge branch '2.8' into 3.3

* 2.8:
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message

Author: nicolas-grekas

Constraints/ExpressionValidator.php

@@ -45,7 +45,7 @@ public function validate($value, Constraint $constraint)
 
         if (!$this->getExpressionLanguage()->evaluate($constraint->expression, $variables)) {
             $this->context->buildViolation($constraint->message)
-                ->setParameter('{{ value }}', $this->formatValue($value))
+                ->setParameter('{{ value }}', $this->formatValue($value, self::OBJECT_TO_STRING))
                 ->setCode(Expression::EXPRESSION_FAILED_ERROR)
                 ->addViolation();
         }

Tests/Constraints/ExpressionValidatorTest.php

@@ -15,6 +15,7 @@
 use Symfony\Component\Validator\Constraints\ExpressionValidator;
 use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;
 use Symfony\Component\Validator\Tests\Fixtures\Entity;
+use Symfony\Component\Validator\Tests\Fixtures\ToString;
 
 class ExpressionValidatorTest extends ConstraintValidatorTestCase
 {
@@ -87,6 +88,40 @@ public function testFailingExpressionAtObjectLevel()
             ->assertRaised();
     }
 
+    public function testSucceedingExpressionAtObjectLevelWithToString()
+    {
+        $constraint = new Expression('this.data == 1');
+
+        $object = new ToString();
+        $object->data = '1';
+
+        $this->setObject($object);
+
+        $this->validator->validate($object, $constraint);
+
+        $this->assertNoViolation();
+    }
+
+    public function testFailingExpressionAtObjectLevelWithToString()
+    {
+        $constraint = new Expression(array(
+            'expression' => 'this.data == 1',
+            'message' => 'myMessage',
+        ));
+
+        $object = new ToString();
+        $object->data = '2';
+
+        $this->setObject($object);
+
+        $this->validator->validate($object, $constraint);
+
+        $this->buildViolation('myMessage')
+            ->setParameter('{{ value }}', 'toString')
+            ->setCode(Expression::EXPRESSION_FAILED_ERROR)
+            ->assertRaised();
+    }
+
     public function testSucceedingExpressionAtPropertyLevel()
     {
         $constraint = new Expression('value == this.data');

Tests/Fixtures/ToString.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Validator\Tests\Fixtures;
+
+class ToString
+{
+    public $data;
+
+    public function __toString()
+    {
+        return 'toString';
+    }
+}